An improved structure for an amplifier comprises: a single member, which at least has a frame, an edge and a membrane; and a positioning shrapnel, which is assembled by an inner frame, an outer frame and a plurality of flexible braces, the outer frame is firmly disposed at the frame of the single member, the plurality of flexible braces is disposed between the inner frame and the outer frame, the inner frame is firmly disposed on the membrane of the single member, wherein the peripheral of the frame has a fillister that can be embedded in by the outer frame, each connection of any of the flexible braces and the inner frame is a curve portion that is to keep the connection of the inner frame and the outer frame while a height difference is existed between the inner frame and the outer frame.